/Engine/Source/Runtime/Slate/Public/Framework/Application/IWidgetReflector.h
Take a snapshot of the UI pertaining to the widget that the user is hovering and visualize it. If we are not taking a snapshot, draw the overlay from a previous snapshot, if possible.
The maximum layer ID that we attained while painting the overlay.
int32 Visualize ( const [FWidgetPath](API\Runtime\SlateCore\Layout\FWidgetPath) & InWidgetsToVisualize, [FSlateWindowElementList](API\Runtime\SlateCore\Rendering\FSlateWindowElementList) & OutDrawElements, int32 LayerId )